]>
git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - arch/um/kernel/trap.c
2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
7 #include <linux/sched.h>
8 #include <linux/hardirq.h>
9 #include <linux/module.h>
10 #include <asm/current.h>
11 #include <asm/pgtable.h>
12 #include <asm/tlbflush.h>
14 #include <as-layout.h>
15 #include <kern_util.h>
20 * Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by
23 int handle_page_fault(unsigned long address
, unsigned long ip
,
24 int is_write
, int is_user
, int *code_out
)
26 struct mm_struct
*mm
= current
->mm
;
27 struct vm_area_struct
*vma
;
33 unsigned int flags
= FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_KILLABLE
|
34 (is_write
? FAULT_FLAG_WRITE
: 0);
36 *code_out
= SEGV_MAPERR
;
39 * If the fault was during atomic operation, don't take the fault, just
46 down_read(&mm
->mmap_sem
);
47 vma
= find_vma(mm
, address
);
50 else if (vma
->vm_start
<= address
)
52 else if (!(vma
->vm_flags
& VM_GROWSDOWN
))
54 else if (is_user
&& !ARCH_IS_STACKGROW(address
))
56 else if (expand_stack(vma
, address
))
60 *code_out
= SEGV_ACCERR
;
61 if (is_write
&& !(vma
->vm_flags
& VM_WRITE
))
64 /* Don't require VM_READ|VM_EXEC for write faults! */
65 if (!is_write
&& !(vma
->vm_flags
& (VM_READ
| VM_EXEC
)))
71 fault
= handle_mm_fault(mm
, vma
, address
, flags
);
73 if ((fault
& VM_FAULT_RETRY
) && fatal_signal_pending(current
))
76 if (unlikely(fault
& VM_FAULT_ERROR
)) {
77 if (fault
& VM_FAULT_OOM
) {
79 } else if (fault
& VM_FAULT_SIGBUS
) {
85 if (flags
& FAULT_FLAG_ALLOW_RETRY
) {
86 if (fault
& VM_FAULT_MAJOR
)
90 if (fault
& VM_FAULT_RETRY
) {
91 flags
&= ~FAULT_FLAG_ALLOW_RETRY
;
92 flags
|= FAULT_FLAG_TRIED
;
98 pgd
= pgd_offset(mm
, address
);
99 pud
= pud_offset(pgd
, address
);
100 pmd
= pmd_offset(pud
, address
);
101 pte
= pte_offset_kernel(pmd
, address
);
102 } while (!pte_present(*pte
));
105 * The below warning was added in place of
106 * pte_mkyoung(); if (is_write) pte_mkdirty();
107 * If it's triggered, we'd see normally a hang here (a clean pte is
108 * marked read-only to emulate the dirty bit).
109 * However, the generic code can mark a PTE writable but clean on a
110 * concurrent read fault, triggering this harmlessly. So comment it out.
113 WARN_ON(!pte_young(*pte
) || (is_write
&& !pte_dirty(*pte
)));
115 flush_tlb_page(vma
, address
);
117 up_read(&mm
->mmap_sem
);
123 * We ran out of memory, call the OOM killer, and return the userspace
124 * (which will retry the fault, or kill us if we got oom-killed).
126 up_read(&mm
->mmap_sem
);
127 pagefault_out_of_memory();
130 EXPORT_SYMBOL(handle_page_fault
);
132 static void show_segv_info(struct uml_pt_regs
*regs
)
134 struct task_struct
*tsk
= current
;
135 struct faultinfo
*fi
= UPT_FAULTINFO(regs
);
137 if (!unhandled_signal(tsk
, SIGSEGV
))
140 if (!printk_ratelimit())
143 printk("%s%s[%d]: segfault at %lx ip %p sp %p error %x",
144 task_pid_nr(tsk
) > 1 ? KERN_INFO
: KERN_EMERG
,
145 tsk
->comm
, task_pid_nr(tsk
), FAULT_ADDRESS(*fi
),
146 (void *)UPT_IP(regs
), (void *)UPT_SP(regs
),
149 print_vma_addr(KERN_CONT
" in ", UPT_IP(regs
));
150 printk(KERN_CONT
"\n");
153 static void bad_segv(struct faultinfo fi
, unsigned long ip
)
157 si
.si_signo
= SIGSEGV
;
158 si
.si_code
= SEGV_ACCERR
;
159 si
.si_addr
= (void __user
*) FAULT_ADDRESS(fi
);
160 current
->thread
.arch
.faultinfo
= fi
;
161 force_sig_info(SIGSEGV
, &si
, current
);
164 void fatal_sigsegv(void)
166 force_sigsegv(SIGSEGV
, current
);
169 * This is to tell gcc that we're not returning - do_signal
170 * can, in general, return, but in this case, it's not, since
171 * we just got a fatal SIGSEGV queued.
176 void segv_handler(int sig
, struct siginfo
*unused_si
, struct uml_pt_regs
*regs
)
178 struct faultinfo
* fi
= UPT_FAULTINFO(regs
);
180 if (UPT_IS_USER(regs
) && !SEGV_IS_FIXABLE(fi
)) {
181 show_segv_info(regs
);
182 bad_segv(*fi
, UPT_IP(regs
));
185 segv(*fi
, UPT_IP(regs
), UPT_IS_USER(regs
), regs
);
189 * We give a *copy* of the faultinfo in the regs to segv.
190 * This must be done, since nesting SEGVs could overwrite
191 * the info in the regs. A pointer to the info then would
194 unsigned long segv(struct faultinfo fi
, unsigned long ip
, int is_user
,
195 struct uml_pt_regs
*regs
)
200 int is_write
= FAULT_WRITE(fi
);
201 unsigned long address
= FAULT_ADDRESS(fi
);
203 if (!is_user
&& (address
>= start_vm
) && (address
< end_vm
)) {
204 flush_tlb_kernel_vm();
207 else if (current
->mm
== NULL
) {
208 show_regs(container_of(regs
, struct pt_regs
, regs
));
209 panic("Segfault with no mm");
212 if (SEGV_IS_FIXABLE(&fi
) || SEGV_MAYBE_FIXABLE(&fi
))
213 err
= handle_page_fault(address
, ip
, is_write
, is_user
,
218 * A thread accessed NULL, we get a fault, but CR2 is invalid.
219 * This code is used in __do_copy_from_user() of TT mode.
220 * XXX tt mode is gone, so maybe this isn't needed any more
225 catcher
= current
->thread
.fault_catcher
;
228 else if (catcher
!= NULL
) {
229 current
->thread
.fault_addr
= (void *) address
;
230 UML_LONGJMP(catcher
, 1);
232 else if (current
->thread
.fault_addr
!= NULL
)
233 panic("fault_addr set but no fault catcher");
234 else if (!is_user
&& arch_fixup(ip
, regs
))
238 show_regs(container_of(regs
, struct pt_regs
, regs
));
239 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
243 show_segv_info(regs
);
245 if (err
== -EACCES
) {
246 si
.si_signo
= SIGBUS
;
248 si
.si_code
= BUS_ADRERR
;
249 si
.si_addr
= (void __user
*)address
;
250 current
->thread
.arch
.faultinfo
= fi
;
251 force_sig_info(SIGBUS
, &si
, current
);
253 BUG_ON(err
!= -EFAULT
);
254 si
.si_signo
= SIGSEGV
;
255 si
.si_addr
= (void __user
*) address
;
256 current
->thread
.arch
.faultinfo
= fi
;
257 force_sig_info(SIGSEGV
, &si
, current
);
262 void relay_signal(int sig
, struct siginfo
*si
, struct uml_pt_regs
*regs
)
264 struct faultinfo
*fi
;
265 struct siginfo clean_si
;
267 if (!UPT_IS_USER(regs
)) {
269 printk(KERN_ERR
"Bus error - the host /dev/shm or /tmp "
270 "mount likely just ran out of space\n");
271 panic("Kernel mode signal %d", sig
);
274 arch_examine_signal(sig
, regs
);
276 memset(&clean_si
, 0, sizeof(clean_si
));
277 clean_si
.si_signo
= si
->si_signo
;
278 clean_si
.si_errno
= si
->si_errno
;
279 clean_si
.si_code
= si
->si_code
;
286 fi
= UPT_FAULTINFO(regs
);
287 clean_si
.si_addr
= (void __user
*) FAULT_ADDRESS(*fi
);
288 current
->thread
.arch
.faultinfo
= *fi
;
289 #ifdef __ARCH_SI_TRAPNO
290 clean_si
.si_trapno
= si
->si_trapno
;
294 printk(KERN_ERR
"Attempted to relay unknown signal %d (si_code = %d)\n",
298 force_sig_info(sig
, &clean_si
, current
);
301 void bus_handler(int sig
, struct siginfo
*si
, struct uml_pt_regs
*regs
)
303 if (current
->thread
.fault_catcher
!= NULL
)
304 UML_LONGJMP(current
->thread
.fault_catcher
, 1);
306 relay_signal(sig
, si
, regs
);
309 void winch(int sig
, struct siginfo
*unused_si
, struct uml_pt_regs
*regs
)
311 do_IRQ(WINCH_IRQ
, regs
);